250 lines
6.7 KiB
Go
250 lines
6.7 KiB
Go
package imaging
|
|
|
|
import (
|
|
"bytes"
|
|
"image"
|
|
"image/color"
|
|
"math"
|
|
)
|
|
|
|
// New creates a new image with the specified width and height, and fills it with the specified color.
|
|
func New(width, height int, fillColor color.Color) *image.NRGBA {
|
|
if width <= 0 || height <= 0 {
|
|
return &image.NRGBA{}
|
|
}
|
|
|
|
c := color.NRGBAModel.Convert(fillColor).(color.NRGBA)
|
|
if (c == color.NRGBA{0, 0, 0, 0}) {
|
|
return image.NewNRGBA(image.Rect(0, 0, width, height))
|
|
}
|
|
|
|
return &image.NRGBA{
|
|
Pix: bytes.Repeat([]byte{c.R, c.G, c.B, c.A}, width*height),
|
|
Stride: 4 * width,
|
|
Rect: image.Rect(0, 0, width, height),
|
|
}
|
|
}
|
|
|
|
// Clone returns a copy of the given image.
|
|
func Clone(img image.Image) *image.NRGBA {
|
|
src := newScanner(img)
|
|
dst := image.NewNRGBA(image.Rect(0, 0, src.w, src.h))
|
|
size := src.w * 4
|
|
parallel(0, src.h, func(ys <-chan int) {
|
|
for y := range ys {
|
|
i := y * dst.Stride
|
|
src.scan(0, y, src.w, y+1, dst.Pix[i:i+size])
|
|
}
|
|
})
|
|
return dst
|
|
}
|
|
|
|
// Anchor is the anchor point for image alignment.
|
|
type Anchor int
|
|
|
|
// Anchor point positions.
|
|
const (
|
|
Center Anchor = iota
|
|
TopLeft
|
|
Top
|
|
TopRight
|
|
Left
|
|
Right
|
|
BottomLeft
|
|
Bottom
|
|
BottomRight
|
|
)
|
|
|
|
func anchorPt(b image.Rectangle, w, h int, anchor Anchor) image.Point {
|
|
var x, y int
|
|
switch anchor {
|
|
case TopLeft:
|
|
x = b.Min.X
|
|
y = b.Min.Y
|
|
case Top:
|
|
x = b.Min.X + (b.Dx()-w)/2
|
|
y = b.Min.Y
|
|
case TopRight:
|
|
x = b.Max.X - w
|
|
y = b.Min.Y
|
|
case Left:
|
|
x = b.Min.X
|
|
y = b.Min.Y + (b.Dy()-h)/2
|
|
case Right:
|
|
x = b.Max.X - w
|
|
y = b.Min.Y + (b.Dy()-h)/2
|
|
case BottomLeft:
|
|
x = b.Min.X
|
|
y = b.Max.Y - h
|
|
case Bottom:
|
|
x = b.Min.X + (b.Dx()-w)/2
|
|
y = b.Max.Y - h
|
|
case BottomRight:
|
|
x = b.Max.X - w
|
|
y = b.Max.Y - h
|
|
default:
|
|
x = b.Min.X + (b.Dx()-w)/2
|
|
y = b.Min.Y + (b.Dy()-h)/2
|
|
}
|
|
return image.Pt(x, y)
|
|
}
|
|
|
|
// Crop cuts out a rectangular region with the specified bounds
|
|
// from the image and returns the cropped image.
|
|
func Crop(img image.Image, rect image.Rectangle) *image.NRGBA {
|
|
r := rect.Intersect(img.Bounds()).Sub(img.Bounds().Min)
|
|
if r.Empty() {
|
|
return &image.NRGBA{}
|
|
}
|
|
src := newScanner(img)
|
|
dst := image.NewNRGBA(image.Rect(0, 0, r.Dx(), r.Dy()))
|
|
rowSize := r.Dx() * 4
|
|
parallel(r.Min.Y, r.Max.Y, func(ys <-chan int) {
|
|
for y := range ys {
|
|
i := (y - r.Min.Y) * dst.Stride
|
|
src.scan(r.Min.X, y, r.Max.X, y+1, dst.Pix[i:i+rowSize])
|
|
}
|
|
})
|
|
return dst
|
|
}
|
|
|
|
// CropAnchor cuts out a rectangular region with the specified size
|
|
// from the image using the specified anchor point and returns the cropped image.
|
|
func CropAnchor(img image.Image, width, height int, anchor Anchor) *image.NRGBA {
|
|
srcBounds := img.Bounds()
|
|
pt := anchorPt(srcBounds, width, height, anchor)
|
|
r := image.Rect(0, 0, width, height).Add(pt)
|
|
b := srcBounds.Intersect(r)
|
|
return Crop(img, b)
|
|
}
|
|
|
|
// CropCenter cuts out a rectangular region with the specified size
|
|
// from the center of the image and returns the cropped image.
|
|
func CropCenter(img image.Image, width, height int) *image.NRGBA {
|
|
return CropAnchor(img, width, height, Center)
|
|
}
|
|
|
|
// Paste pastes the img image to the background image at the specified position and returns the combined image.
|
|
func Paste(background, img image.Image, pos image.Point) *image.NRGBA {
|
|
dst := Clone(background)
|
|
pos = pos.Sub(background.Bounds().Min)
|
|
pasteRect := image.Rectangle{Min: pos, Max: pos.Add(img.Bounds().Size())}
|
|
interRect := pasteRect.Intersect(dst.Bounds())
|
|
if interRect.Empty() {
|
|
return dst
|
|
}
|
|
src := newScanner(img)
|
|
parallel(interRect.Min.Y, interRect.Max.Y, func(ys <-chan int) {
|
|
for y := range ys {
|
|
x1 := interRect.Min.X - pasteRect.Min.X
|
|
x2 := interRect.Max.X - pasteRect.Min.X
|
|
y1 := y - pasteRect.Min.Y
|
|
y2 := y1 + 1
|
|
i1 := y*dst.Stride + interRect.Min.X*4
|
|
i2 := i1 + interRect.Dx()*4
|
|
src.scan(x1, y1, x2, y2, dst.Pix[i1:i2])
|
|
}
|
|
})
|
|
return dst
|
|
}
|
|
|
|
// PasteCenter pastes the img image to the center of the background image and returns the combined image.
|
|
func PasteCenter(background, img image.Image) *image.NRGBA {
|
|
bgBounds := background.Bounds()
|
|
bgW := bgBounds.Dx()
|
|
bgH := bgBounds.Dy()
|
|
bgMinX := bgBounds.Min.X
|
|
bgMinY := bgBounds.Min.Y
|
|
|
|
centerX := bgMinX + bgW/2
|
|
centerY := bgMinY + bgH/2
|
|
|
|
x0 := centerX - img.Bounds().Dx()/2
|
|
y0 := centerY - img.Bounds().Dy()/2
|
|
|
|
return Paste(background, img, image.Pt(x0, y0))
|
|
}
|
|
|
|
// Overlay draws the img image over the background image at given position
|
|
// and returns the combined image. Opacity parameter is the opacity of the img
|
|
// image layer, used to compose the images, it must be from 0.0 to 1.0.
|
|
//
|
|
// Examples:
|
|
//
|
|
// // Draw spriteImage over backgroundImage at the given position (x=50, y=50).
|
|
// dstImage := imaging.Overlay(backgroundImage, spriteImage, image.Pt(50, 50), 1.0)
|
|
//
|
|
// // Blend two opaque images of the same size.
|
|
// dstImage := imaging.Overlay(imageOne, imageTwo, image.Pt(0, 0), 0.5)
|
|
//
|
|
func Overlay(background, img image.Image, pos image.Point, opacity float64) *image.NRGBA {
|
|
opacity = math.Min(math.Max(opacity, 0.0), 1.0) // Ensure 0.0 <= opacity <= 1.0.
|
|
dst := Clone(background)
|
|
pos = pos.Sub(background.Bounds().Min)
|
|
pasteRect := image.Rectangle{Min: pos, Max: pos.Add(img.Bounds().Size())}
|
|
interRect := pasteRect.Intersect(dst.Bounds())
|
|
if interRect.Empty() {
|
|
return dst
|
|
}
|
|
src := newScanner(img)
|
|
parallel(interRect.Min.Y, interRect.Max.Y, func(ys <-chan int) {
|
|
scanLine := make([]uint8, interRect.Dx()*4)
|
|
for y := range ys {
|
|
x1 := interRect.Min.X - pasteRect.Min.X
|
|
x2 := interRect.Max.X - pasteRect.Min.X
|
|
y1 := y - pasteRect.Min.Y
|
|
y2 := y1 + 1
|
|
src.scan(x1, y1, x2, y2, scanLine)
|
|
i := y*dst.Stride + interRect.Min.X*4
|
|
j := 0
|
|
for x := interRect.Min.X; x < interRect.Max.X; x++ {
|
|
d := dst.Pix[i : i+4 : i+4]
|
|
r1 := float64(d[0])
|
|
g1 := float64(d[1])
|
|
b1 := float64(d[2])
|
|
a1 := float64(d[3])
|
|
|
|
s := scanLine[j : j+4 : j+4]
|
|
r2 := float64(s[0])
|
|
g2 := float64(s[1])
|
|
b2 := float64(s[2])
|
|
a2 := float64(s[3])
|
|
|
|
coef2 := opacity * a2 / 255
|
|
coef1 := (1 - coef2) * a1 / 255
|
|
coefSum := coef1 + coef2
|
|
coef1 /= coefSum
|
|
coef2 /= coefSum
|
|
|
|
d[0] = uint8(r1*coef1 + r2*coef2)
|
|
d[1] = uint8(g1*coef1 + g2*coef2)
|
|
d[2] = uint8(b1*coef1 + b2*coef2)
|
|
d[3] = uint8(math.Min(a1+a2*opacity*(255-a1)/255, 255))
|
|
|
|
i += 4
|
|
j += 4
|
|
}
|
|
}
|
|
})
|
|
return dst
|
|
}
|
|
|
|
// OverlayCenter overlays the img image to the center of the background image and
|
|
// returns the combined image. Opacity parameter is the opacity of the img
|
|
// image layer, used to compose the images, it must be from 0.0 to 1.0.
|
|
func OverlayCenter(background, img image.Image, opacity float64) *image.NRGBA {
|
|
bgBounds := background.Bounds()
|
|
bgW := bgBounds.Dx()
|
|
bgH := bgBounds.Dy()
|
|
bgMinX := bgBounds.Min.X
|
|
bgMinY := bgBounds.Min.Y
|
|
|
|
centerX := bgMinX + bgW/2
|
|
centerY := bgMinY + bgH/2
|
|
|
|
x0 := centerX - img.Bounds().Dx()/2
|
|
y0 := centerY - img.Bounds().Dy()/2
|
|
|
|
return Overlay(background, img, image.Point{x0, y0}, opacity)
|
|
}
|